U.S. patent application number 14/033910 was filed with the patent office on 2014-01-23 for tuning fork vibrator.
This patent application is currently assigned to FUJITSU LIMITED. The applicant listed for this patent is FUJITSU LIMITED. Invention is credited to Masayuki Itoh, Masakazu Kishi, Hajime Kubota.
Application Number | 20140021829 14/033910 |
Document ID | / |
Family ID | 46878877 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140021829 |
Kind Code |
A1 |
Kubota; Hajime ; et
al. |
January 23, 2014 |
TUNING FORK VIBRATOR
Abstract
A tuning fork vibrator includes a package having an internal
space having a rectangle column shape; a tuning fork vibration
piece including a base, two vibration arms extending in parallel
form the base and a first arm and a second arm extending obliquely
from the base so as to interpose the two vibration arms, the tuning
fork vibration piece having a length from the base to a tip in an
extended direction of the two vibration arms which is longer than
each side of the bottom surface of the internal space, wherein the
tuning fork vibration piece is placed in the internal space with
the extended direction set along a diagonal direction of the
internal space, and a tip part of the first arm and a tip part of
the second arm of the tuning fork vibration piece are fixed to the
bottom surface of the internal space.
Inventors: |
Kubota; Hajime; (Kawasaki,
JP) ; Itoh; Masayuki; (Kawasaki, JP) ; Kishi;
Masakazu; (Kawasaki, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJITSU LIMITED |
Kawasaki-shi |
|
JP |
|
|
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
46878877 |
Appl. No.: |
14/033910 |
Filed: |
September 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/057201 |
Mar 24, 2011 |
|
|
|
14033910 |
|
|
|
|
Current U.S.
Class: |
310/351 ;
310/365; 310/370 |
Current CPC
Class: |
H01L 41/0472 20130101;
H03H 9/215 20130101; H01L 41/053 20130101; H01L 41/107 20130101;
H03H 9/21 20130101; H03H 9/1021 20130101 |
Class at
Publication: |
310/351 ;
310/370; 310/365 |
International
Class: |
H01L 41/053 20060101
H01L041/053; H01L 41/047 20060101 H01L041/047; H01L 41/107 20060101
H01L041/107 |
Claims
1. A tuning fork vibrator, comprising: a package having an internal
space having a rectangle column shape; a tuning fork vibration
piece including a base, two vibration arms extending in parallel
form the base and a first arm and a second arm extending obliquely
from the base so as to interpose the two vibration arms, the tuning
fork vibration piece having a length from the base to a tip in an
extended direction of the two vibration arms which is longer than
each side of the bottom surface of the internal space, wherein the
tuning fork vibration piece is placed in the internal space with
the extended direction set along a diagonal direction of the
internal space, and a tip part of the first arm and a tip part of
the second arm of the tuning fork vibration piece are fixed to the
bottom surface of the internal space.
2. The tuning fork vibrator according to claim 1, wherein the
tuning fork vibrating piece includes: a first excitation electrode
and a second excitation electrode that are respectively provided on
the two vibrating arms, respectively; a first terminal that is
provided on an undersurface of the tip part of the first fixed arm
and is electrically connected to the first excitation electrode;
and a second terminal that is provided on an undersurface of the
tip part of the second fixed arm and is electrically connected to
the second excitation electrode, the package includes: a first
mounting terminal and a second mounting terminal that are provided
on an external surface of the package; a first installation
terminal that is electrically connected to the first excitation
electrode and is provided on a part of the bottom face, which faces
the first terminal when the tuning fork vibrating piece is placed
in the internal space; and a second installation terminal that is
electrically connected to the second excitation electrode and is
provided on a part of the bottom face, which faces the second
terminal when the tuning fork vibrating piece is placed in the
internal space, and the undersurface of the tip part of the first
fixed arm and the undersurface of the tip part of the second fixed
arm are fixed to the first installation terminal and the second
installation terminal by a electrically conductive adhesive,
respectively.
3. The tuning fork vibrator according to claim 1, wherein the
tuning fork vibrating piece has such a shape that a plane that
passes through the center of gravity of the tuning fork vibrating
piece and is perpendicular to the extending direction crosses the
tip part of the first fixed arm and the tip part of the second
fixed arm.
4. The tuning fork vibrator according to claim 1, wherein the
tuning fork vibrating piece have a plane symmetrical shape with
respect to a plane positioned at the center of the two vibrating
arms.
5. The tuning fork vibrator according to claim 1, wherein a groove
is formed in one surface of each vibrating arm of the tuning fork
vibrating piece, and an excitation electrode is formed inside the
groove of each vibrating arm of the tuning fork vibrating
piece.
6. A tuning fork vibrator, comprising: a package; and a tuning fork
vibrating piece that is placed in the package and includes a base,
two vibration arms extending in parallel form the base, and two
fixed arms extending obliquely from the base so as to interpose the
two vibration arms, wherein each of the two vibration arms of the
tuning fork vibrating piece has a U-shape that extends in a
specific direction, bents toward a direction separating from a
mounting surface of the tuning fork vibrating piece onto the
package, and then extends in a direction opposite to the specific
direction.
7. The tuning fork vibrator according to claim 6, wherein the
tuning fork vibrating piece has such a shape that each of the two
fixed arms extends obliquely from the base and a length in an
extended direction of the two vibration arms is longer than each
side of a bottom surface of an internal space of the package, the
tuning fork vibration piece is placed in the internal space of the
package with the extended direction set along a diagonal direction
of the internal space, and a tip part of each of the two fixed arms
of the tuning fork vibration piece is fixed to the bottom surface
of the internal space.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of
International Application PCT/JP2011/057201 filed on Mar. 24, 2011
and designated the U.S., the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The present invention relates to a tuning fork vibrator.
BACKGROUND
[0003] As tuning fork vibrators used for cellular phones, watches,
etc., a 3215-size tuning fork vibrator (a tuning fork vibrator
whose package size is 3.2 mm.times.1.5 mm; the same shall applies
hereinafter) and a 2012-size tuning fork vibrator are commercially
available.
[0004] The general 3215-size tuning fork vibrator is configured by
placing a tuning fork vibrating piece illustrated in FIG. 1, i.e.,
a tuning fork vibrating piece having two vibrating arms 82 extended
from a base 81, in a package in such a way that its longitudinal
direction is aligned with the longitudinal direction of the
package.
[0005] Further, a tuning fork vibrating piece depicted in FIG. 2,
i.e., a tuning fork vibrating piece having a fixed arm 83 added to
the outside of each vibrating arm 82, is generally used in the
2012-size tuning fork vibrator. Moreover, the 2012-size tuning fork
vibrator is configured by housing the tuning fork vibrating piece
in the package in such a way that its longitudinal direction is
aligned with the longitudinal direction of the package and fixing
each fixed arm 83 of the tuning fork vibrating piece to the inner
bottom surface of the package.
PRIOR ART REFERENCE
[0006] Patent Document 1: Japanese Examined Patent Application
Publication No. 11-23285
[0007] Patent Document 2: Japanese Examined Patent Application
Publication No. 2004-297198
[0008] Patent Document 3: Japanese Examined Patent Application
Publication No. 2006-308498
[0009] Patent Document 4: Japanese Examined Patent Application
Publication No. 2008-022413
[0010] Most devices in which the tuning fork vibrators are used are
small. Therefore, to provide a small tuning fork vibrator has been
desired. However, it is difficult to obtain a tuning fork vibrator
having short vibrating arms with a high oscillation stability (with
a small CI (Crystal Impedance) value).
[0011] As illustrated in FIG. 3, housing the tuning fork vibrating
piece obliquely in the package 60 allows each vibrating arm 82 to
be lengthened. However, with this structure, the distance between
the tip of each vibrating arm 82 and the inner wall surface of the
package 60 is forced to shorten. Further, the tuning fork vibrating
piece whose base 81 is fixed to the package can vibrate on the base
81. That is, housing the tuning fork vibrating piece obliquely in
the package 60 causes a situation where the tip of each vibrating
arm 82 is easy to contact with the inner surface of the package 60
when external force is applied. Consequently, a stable oscillation
at a predetermined frequency cannot be obtained just by housing the
tuning fork vibrating piece obliquely in the package 60.
SUMMARY
[0012] According to an aspect of the embodiments, A tuning fork
vibrator includes a package having an internal space having a
rectangle column shape; a tuning fork vibration piece including a
base, two vibration arms extending in parallel form the base and a
first arm and a second arm extending obliquely from the base so as
to interpose the two vibration arms, the tuning fork vibration
piece having a length from the base to a tip in an extended
direction of the two vibration arms which is longer than each side
of the bottom surface of the internal space, wherein the tuning
fork vibration piece is placed in the internal space with the
extended direction set along a diagonal direction of the internal
space, and a tip part of the first arm and a tip part of the second
arm of the tuning fork vibration piece are fixed to the bottom
surface of the internal space.
[0013] According to another aspect of the embodiments, a tuning
fork vibrator includes a package; and a tuning fork vibrating piece
that is placed in the package and includes a base, two vibration
arms extending in parallel form the base, and two fixed arms
extending obliquely from the base so as to interpose the two
vibration arms, wherein each of the two vibration arms of the
tuning fork vibrating piece has a U-shape that extends in a
specific direction, bents toward a direction separating from a
mounting surface of the tuning fork vibrating piece onto the
package, and then extends in a direction opposite to the specific
direction.
[0014] The object and advantages of the invention will be realized
and attained by means of the elements and combinations particularly
pointed out in the claims.
[0015] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is a perspective view of an existing tuning fork
vibrating piece;
[0017] FIG. 2 is a perspective view of an existing tuning fork
vibrating piece;
[0018] FIG. 3 is an explanatory diagram of a problem that arises if
a tuning fork vibrating piece consisting of a base and two
vibrating arms is arranged obliquely in a package;
[0019] FIG. 4 is a schematic structural view of a tuning fork
vibrator according to a first embodiment;
[0020] FIG. 5 is a top view of a tuning fork vibrating piece used
in the tuning fork vibrator according to the first embodiment;
[0021] FIG. 6 is a sectional view for explaining a layout example
of excitation electrodes;
[0022] FIG. 7 is a sectional view for explaining another layout
example of excitation electrodes;
[0023] FIG. 8 is an explanatory diagram of a working effect related
to the tuning fork vibrator according to the first embodiment;
[0024] FIG. 9 is a schematic structural view of a tuning fork
vibrator according to a second embodiment;
[0025] FIG. 10 is a perspective view of a tuning fork vibrating
piece used in a tuning fork vibrator according to a third
embodiment;
[0026] FIG. 11A is an explanatory diagram of a manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0027] FIG. 11B is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0028] FIG. 11C is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0029] FIG. 11D is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0030] FIG. 11E is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0031] FIG. 11F is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment;
[0032] FIG. 11G is an explanatory diagram of the manufacturing
procedure example of the tuning fork vibrating piece according to
the third embodiment; and
[0033] FIG. 12 is a perspective view of the tuning fork vibrating
piece used in a tuning fork vibrator according to the fourth
embodiment.
DESCRIPTION OF EMBODIMENTS
[0034] Four types of tuning fork vibrators (hereinafter be denoted
tuning fork vibrators according to a first through forth
embodiment) developed by the inventors will hereinafter be
described with reference to the drawings.
First Embodiment
[0035] FIG. 4 illustrates a schematic structure of a tuning fork
vibrator 11 according to the first embodiment. Note that, in FIG. 4
and each of other FIGS which will be used below, scale of each part
has been modified arbitrarily to make each part of the tuning fork
vibrator 11 etc. easy to recognize.
[0036] As depicted in FIG. 4, the tuning fork vibrator 11 according
to the first embodiment is a surface mounting type tuning fork
vibrator configured by housing a tuning fork vibrating piece 20 in
an internal space 62 of a package 60.
[0037] The package 60 is a case of the tuning fork vibrating piece
20, which includes as main components a box-like member 61 and a
member (not shown; hereinafter be termed a lid part) that functions
as a lid of the box-like member 61
[0038] The box-like member 61 of the package 60 has a concave
portion that forms a rectangle column-shaped internal space 62 when
sealed with the lid part. On the undersurface (under means the
depth direction of the paper surface of FIG. 4) of the box-like
member 61, provided are a first mounting terminal 63.sub.1 and a
second mounting terminal 63.sub.2, which are to be connected with a
drive circuit for the tuning fork vibrator 11. Further, on the
bottom surface of the concave portion of the box-like member 61 (on
the bottom surface of the internal space 62 of the package 60),
provided are a first installation terminal 64.sub.1 and a second
installation terminal 64.sub.2 which are electrically connected to
the first mounting terminal 63.sub.1 and the second mounting
terminal 63.sub.2 via a through hole etc., respectively.
[0039] The tuning fork vibrating piece 20 is a crystal oscillator
manufactured by processing a crystal piece in the same procedure
(method) as a general tuning fork vibrating piece.
[0040] As depicted in FIG. 4, the tuning fork vibrating piece 20
includes a base 21, and two vibrating arms 22.sub.1 and 22.sub.2
extending in parallel from the base 21. Furthermore, the tuning
fork vibrating piece 20 includes a first fixed arm 23.sub.1 and a
second fixed arm 23.sub.2 extending obliquely from the base 21 so
as to interpose the two vibrating arms 22.sub.1 and 22.sub.2.
[0041] Hereinafter, for convenience of explanation, the vibrating
arm 22.sub.1 or the vibrating arm 22.sub.2 is called the vibrating
arm 22, and the extending direction of each vibrating arm 22 is
called the front-back direction. Further, a part consisting of the
base 21 and the two vibrating arms 22 of the tuning fork vibrating
piece 20 is called a body part, and the bottom surface of the
internal space 62 of the package is called the mounting surface.
Moreover, the first fixed arm 23.sub.1 or the second fixed arm
23.sub.2 is called the fixed arm 23, and the first mounting
terminal 63.sub.1 or the like is also called in the same way.
[0042] As illustrated in FIG. 4, the tuning fork vibrating piece 20
has a length in the front-back direction larger than the longer
side of the mounting surface. Therefore, the tuning fork vibrating
piece 20 can be housed within the internal space 62 only in the
form where the front-back direction is along the diagonal direction
of the mounting surface (in the form where the front-back direction
is set almost parallel to the diagonal direction of the mounting
surface).
[0043] Further, the shape of each fixed arm 23 of the tuning fork
vibrating piece 20 is determined so that a plane 72 which passes
through the center of gravity of the tuning fork vibrating piece 20
and is perpendicular to the front-back direction crosses the tip
part of each fixed arm 23. The shape of each fixed arm 23 is also
determined so that the spacing between the tip parts of the fixed
arms 23 becomes the largest (so that the tip part of each fixed arm
23 is located near the inner wall of the package 60).
[0044] Moreover, the first fixed arm 23.sub.1 and the second fixed
arm 23.sub.2 has mirror symmetry in relation to a plane 71 that is
located at the center of the two vibrating arms 22. The body part
also has a plane symmetrical shape with respect to the plane 71.
Therefore, the overall shape of the tuning fork vibrating piece 20
has a plane symmetrical shape with respect to the plane 71.
[0045] As illustrated in FIG. 5, two kinds (two systems) of
excitation electrodes 25.sub.1 and 25.sub.2 are formed on the
surfaces of each vibrating arm 22 of the tuning fork vibrating
piece 20. Further, the first terminal 26.sub.1 electrically
connected with the excitation electrode 25.sub.1 is provided on the
tip part (hereinafter referred to as the first tip part) of the
undersurface of the first fixed arm 23.sub.1 of the tuning fork
vibrating piece 20. Moreover, the second terminal 26.sub.2
electrically connected with the excitation electrode 25.sub.2 is
provided on the tip part (hereafter referred to as the second tip
part) of the undersurface of the second fixed arm 23.sub.2 of the
tuning fork vibrating piece 20.
[0046] Note that, as a shape of each excitation electrode 25
(25.sub.1, 25.sub.2), any shape can be used as long as it can make
the two vibration arms 22 perform flexion vibration. Therefore, a
shape of each excitation electrode (a way to arrange each
excitation electrode 25 on each surface of each vibrating arm 22)
may be the one schematically illustrated in FIG. 6.
However, as schematically illustrated in FIG. 7, it is preferable
to make a groove in the specific surface of each vibrating arm 22
and to form the excitation electrode 25 inside the groove. The
reason is that such structure can cause the CI (Crystal Impedance)
value of the tuning fork vibrator 11 to lower, thereby improving
the oscillation stability of the tuning fork vibrator 11.
[0047] Referring back to FIG. 4, the discussion on the tuning fork
vibrator 11 will continuously proceed.
[0048] The above-mentioned first and second installation terminal
64.sub.1 and 64.sub.2 are respectively provided on the parts which
faces the first terminal 26.sub.1 and the second terminal 26.sub.2
(see FIG. 5) when the tuning fork vibrating piece 20 is housed in
the internal space 62 of the package 60.
[0049] And, the tuning fork vibrator 11 is configured by fixing the
first tip part and the second tip part of the tuning fork vibrating
piece 20 on the first installation terminal 64.sub.1 and the second
installation terminal 64.sub.2 of the package 60 with the
electrically conductive adhesive 68, respectively. Incidentally,
the first tip part is, as already explained (defined), the part on
which the first terminal 26.sub.1 of the first fixed arm 23.sub.1
is formed (the tip part of the undersurface of the first fixed arm
23.sub.1). Further, the second tip part is the part on which the
first terminal 26.sub.2 of the second fixed arm 23.sub.2 is formed
(the tip part of the undersurface of the first fixed arm
23.sub.2).
[0050] As described above, the tuning fork vibrator 11 according to
the first embodiment has such structure that the ratio of length of
the vibrating arm to the package size is larger than that of the
conventional one. Therefore, it can be said that the tuning fork
vibrator 11 according to the first embodiment is a tuning fork
vibrator of which oscillation stability is approximately equal to
that of the conventional one and which is smaller than the
conventional one, a tuning fork vibrator which has a size
approximately equal to that of the conventional one and of which
oscillation stability is higher (CI value is smaller) than that of
conventional one, or the like.
[0051] Moreover, by adopting such structure that the tip parts of
the two fixed arms 23 of the tuning fork vibrating piece 20, which
extend obliquely from the base 21 so as to obliquely from the base
21 so as to interpose the two vibration arms 22, are fixed to the
package, it is possible to prevent the tuning fork vibrating piece
20 from vibrating on the base 21 when an external force is applied.
Further, by adopting such structure that the center of gravity of
the tuning fork vibrating piece 20 is located on the center of two
fixed points of the fixed arms 23, and the spacing between the
fixed points becomes the largest, as schematically illustrated in
FIG. 8, it is possible to lessen the displacement amount of the tip
of each vibrating arm 22 at the time of external force being
applied.
[0052] Consequently, by adopting the above-mentioned structure, it
is possible to provide the tuning fork vibrator which has vibrating
arms of approximately the same length as those of the conventional
one, is smaller than the conventional one, and causes no trouble
resulting from the oblique arrangement of the tuning fork vibrating
piece.
[0053] Moreover, by adopting the above-mentioned structure, it is
also possible to provide the tuning fork vibrator which has the
same size as conventional ones and whose CI value is lower
(oscillation stability is higher) by a value corresponding to an
increment of the length of the vibrating arms. Specifically, in the
existing 3215-size tuning fork vibrator, the tuning fork vibrating
piece whose vibrating arm is about 2 mm in length is usually used.
On the other hand, with the above-mentioned structure, the
3215-size tuning fork vibrator whose vibrating arm is about 2.9 mm
in length, i.e., the 3215-size tuning fork vibrator having the CI
value lower by a value corresponding to 0.9 mm, can be
obtained.
[0054] Further, in the existing 2012-size tuning fork vibrator, the
tuning fork vibrating piece whose vibrating arm is about 1.5 mm in
length is usually used. When the above-mentioned structure is
adopted, it is possible to provide the 2012-size tuning fork
vibrator whose vibrating arm is about 1.73 mm in length, i.e., the
2012-size tuning fork vibrator whose CI value is lower than the
conventional ones by a value corresponding 0.23 mm.
[0055] Finally, design procedure examples of the tuning fork
vibrator 11 will be briefly explained.
[0056] The tuning fork vibrator 11 can be designed by various
procedures. For instance, in a case where the shape of the package
60 is already determined, it is possible to design the tuning fork
vibrating piece 20 in the first procedure described below.
[0057] To begin with, a process of determining the size of a square
area in which the tuning fork vibrating piece is desirable to be
placed, is performed. More specifically, performed is a process of
specifying a square area (hereinafter referred to as a storage
area) smaller than the mounting surface by an amount according to
the error of attaching the tuning fork vibrating piece 20 to the
bottom surface of the package 60, the permissible vibration amount
of the vibrating arm 22 in the case where the external force is
applied, etc. and then determining its size.
[0058] Next, the width (usually 200-300 micrometers) of the body
part (the part consisting of the two vibrating arms 22 and the base
21) is determined. Then, based on the size of the storage area
which has been already determined, the size of the longest
rectangle that is inscribed in the storage area and has the
determined width is determined. Moreover, the tilt angle of the
rectangle to the storage area is determined.
[0059] Subsequently, the shapes of components (the base and the
vibrating arms 22) of the body part are determined from the
obtained size by taking into consideration the obtained tilt angle
(the tilt angle of the longest rectangle having the determined
width to the storage area). Note that the shape determined in this
process is mainly the shape of the base 21 (the length of the base
21 in the front-back direction). Further, the reason why the tilt
angle of the above-mentioned rectangle to the storage area is taken
into consideration is because the length of the boundary portion
between the fixed arms 23 and the body part (in other words,
minimum length of the base 21) changes according to the tilt angle
even if the width of the fixed arm 23 is the same.
[0060] After determining the shape of base 21 etc., the shape
(length and tilt angle from the vibrating arm) of each fixed arm is
determined so that the above condition is satisfied based on the
tilt angle of the storage area of rectangle shape etc., thereby
designing the tuning fork vibrating piece 20.
[0061] Further, in a case where the shape of the package 60 is
already determined, it is also possible to design the tuning fork
vibrating piece 20 in the second procedure described below. Note
that the tuning fork vibrating piece 20 designed in the second
procedure below becomes the one that has the vibrating arm 22
slightly shorter than that of the tuning fork vibrating piece 20
designed in the above-mentioned procedure.
[0062] First, same as in the case of designing the tuning fork
vibrating piece 20 by the first procedure, the size of the storage
area (the square area smaller than the base surface of the internal
space 62 of the package 60 by an amount according to the attachment
error etc.) is determined, and the width of the body part is
determined.
[0063] Next, based on the size of the storage area, the size of the
longest rectangle that is inscribed in the storage area, has the
determined width, and has long sides parallel to the diagonal
direction of the storage area, is determined. Subsequently, the
shapes of components of the body part are determined from the
determined size by taking into consideration the tilt angle of the
diagonal direction of the storage area. Then, the tuning fork
vibrating piece 20 is designed by determining the shape of each
fixed arm 23 on the basis of the tilt angle etc.
[0064] Moreover, it is also possible to design the tuning fork
vibrator 11 in the third procedure described below. Note that the
tuning fork vibrating piece 20 designed in the second procedure
below becomes the one that has the vibrating arm 22 slightly
shorter than that of the tuning fork vibrating piece 20 designed in
the above-mentioned procedure.
[0065] To begin with, the shape of the body part of the tuning fork
vibrating piece 20 is determined. Subsequently, the package 60
which has the internal space 62 of minimum size in which the body
part can be housed is designed by taking the attachment error etc.
into consideration. Incidentally, the package 60 designed in this
process is the one having the internal space 62 in which the body
part is housed obliquely.
[0066] Then, after designing the package 60, the shape of each
fixed arm 23 is designed from the tilt angle of the body part to
the package 60 etc. using the procedure similar to the
above-mentioned procedure, thereby designing the tuning fork
vibrating piece 20.
[0067] Note that, from a viewpoint of matching the terminal
positions (positions of the first terminal 26.sub.1 and the first
installation terminal 64.sub.1, etc.), it is desirable to
manufacture the package 60 by determining the position of each
installation terminal 64 after determining the shape of the tuning
fork vibrating piece 20. However, in a case where the shape of the
tuning fork vibrating piece 20 is determined so that the plane 72
crosses the tip part of each fixed arm 23 and the spacing between
the tip parts of the fixed arms 23 becomes the largest, even if the
housed angle of the tuning fork vibrating piece 20 somewhat
changes, the position of the tip part of each fixed arm 23 hardly
changes. Consequently, it is possible to manufacture the package 60
before determining the shape of the tuning fork vibrating piece 20.
Moreover, it is also possible to manufacture (assemble) the tuning
fork vibrator 11 by combining the package 60 that is manufactured
to the specific-shaped tuning fork vibrating pieces 20 with the
other-shaped tuning fork vibrating piece 20.
Second Embodiment
[0068] FIG. 9 illustrates schematic structure of the tuning fork
vibrator 12 according to the second embodiment is shown.
[0069] The package 60 of this tuning fork vibrator 12 is a package
equivalent to the package 60 for the tuning fork vibrator 12 which
is deformed into the square shape (the right rectangular column
shape).
[0070] The tuning fork vibrating piece 30 of the tuning fork
vibrator 12 is the modified version of tuning fork vibrating piece
20 (FIG. 4) of the tuning fork vibrator 12 modified so as to be
able to arrange on the mounting face having a square shape. In
other words, the tuning fork vibrating piece 30 is a member that is
designed by the second procedure on condition that the mounting
face has a square shape.
[0071] Consequently, it can also be said that the tuning fork
vibrator 12 according to the second embodiment is a tuning fork
vibrator of which oscillation stability is approximately equal to
that of the conventional ones and which is smaller than the
conventional ones, a tuning fork vibrator which has a size
approximately equal to that of the conventional ones and of which
oscillation stability is higher than that of conventional ones, or
the like.
Third Embodiment
[0072] FIG. 10 illustrates structure of a tuning fork vibrating
piece 40 used for the tuning fork vibrator according to the third
embodiment. Note that, in the following discussion, front, back,
left, right, up and down mean directions illustrated in FIG.
10.
[0073] As illustrated in FIG. 10, the tuning fork vibrating piece
40 used for the tuning fork vibrator according to the third
embodiment includes a base 41 and two vibrating arms 42.sub.1 and
42.sub.2 extending in parallel from the base 41. Moreover, the
tuning fork vibrating piece 40 includes a first fixed arm 43.sub.1
extending from the base 11 toward the right direction and then
extending toward the front direction. The tuning fork vibrating
piece 40 also includes a second fixed arm 43.sub.2 extending toward
the front direction and then extending from the base 11 toward the
left direction and then extending toward the front direction.
[0074] Each vibration arm 42 (42.sub.1, 42.sub.2) has a U-shape
that extends in the front direction, bents toward the up direction,
and then extends in the back direction. Moreover, grooves (only
parts of the grooves are illustrated in FIG. 10) are formed on the
three outside surfaces (the uppermost surface, the lowermost
surface and the surface which connects them in FIG. 10).
Incidentally, this tuning fork vibrating piece 40 is manufactured,
for example, so that the width (the length in the left-right
direction) of each vibrating arm 42 becomes 80 micrometers, each of
the width and depth of the groove of each vibrating arm 42 becomes
40 micrometers, and the spacing between the two vibrating arms 42
becomes 50-100 micrometers.
[0075] Two kinds of excitation electrodes 45.sub.1 and 45.sub.2 are
formed on each surface of each vibrating arm 42. Note that, in FIG.
10 and in other figures such as FIG. 12, different patterns are
attached to the excitation electrode 45.sub.1 and the excitation
electrode 45.sub.2 not to indicate that constituent materials for
the excitation electrodes 45 are different, but to make a layout
(connection relationship) of each excitation electrode 45
intelligible.
[0076] On the tip part of the undersurface of the first fixed arm
43.sub.1 of the tuning fork vibrating piece 40, provided is a first
terminal 46.sub.1 that is electrically connected with the
excitation electrode 45.sub.1. On the tip part of the undersurface
of the second fixed arm 43.sub.2 of the tuning fork vibrating piece
40, provided is a first terminal 46.sub.2 that is electrically
connected with the excitation electrode 45.sub.2.
[0077] The tuning fork vibrating piece 40 has the structure
explained above. And, the tuning fork vibrator according to the
third embodiment is configured by housing the tuning fork vibrating
piece 40 in the package so that the front-back direction of the
tuning fork vibrating piece 40 coincides with the longitudinal
direction of the package.
[0078] In short, the tuning fork vibrating piece 40 adapted to the
tuning fork vibrator according to the fourth embodiment is the one
each of whose vibrating arms 42 is bent in order to lengthen each
vibrating arm 42 (the one including the vibrating arms 42 each
having a U-shape).
[0079] The CI value becomes small as the oscillating arm becomes
long. Consequently, use of the tuning fork vibrating piece 40
allows, for example, the 3215-size tuning fork vibrator whose CI
value is small (oscillation instability is high) because the length
of each vibrating arm 42 is about 4.0 mm (twice as long as the
conventional vibrating arm). It is also possible to provide the
2012-size tuning fork vibrator whose CI value is small because the
length of each vibrating arm 42 is about 3.0 mm.
[0080] Moreover, the tuning fork vibrating piece 40 has such
structure that, when the length of each vibrating arm 42 is made
into the same length as the conventional fork vibrating piece
(FIGS. 1 and 2), its length in the front-back direction becomes
half the length of the conventional fork vibrating piece.
[0081] Consequently, by adopting the structure of the tuning fork
vibrator according to the present embodiment, it is possible to
provide the tuning fork vibrator smaller than the conventional
ones.
[0082] As described above, the tuning fork vibrating piece 40 has a
shape more complicated than the general tuning fork vibrating
piece. Therefore, a manufacturing procedure example of the tuning
fork vibrating piece 40 will be explained briefly referring to
FIGS. 11A-11G.
[0083] At the time of manufacturing the tuning fork vibrating piece
40, a first, a quartz crystal (FIG. 11A) of which the length of
respective side is almost the same as the tuning fork vibrating
piece 40 to be manufactured is prepared. Then, a member having a
shape illustrated in FIG. 11B is obtained by etching the quartz
crystal from above (or below). Next, the first fixed arm 43.sub.1
and the second fixed arm 43.sub.2 are formed by processing
(polishing etc.) the right and left portions of the member (FIG.
11C).
[0084] Subsequently, a member having a shape illustrated in FIG.
11D is obtained by etching from above the member in which the fixed
arms 43 are formed. Then, vibrating arms 42.sub.1 and 42.sub.2
having no groove (FIG. 11E) are formed by etching the member from
the side directions (right and left side directions).
[0085] After that, electrode (a part of excitation electrodes 45)
is formed on each surface of the member depicted in FIG. 11E by
sputtering etc. (FIG. 11F), and grooves are formed on the three
outer surface of each vibrating arm 42 (FIG. 11G).
[0086] Then, the tuning fork vibrating piece 40 (FIG. 10) is
manufactured by forming electrodes (parts of the excitation
electrodes 45, the first terminal 46.sub.1, the second terminal
46.sub.2) within the formed grooves and on the tip part of the
undersurface of each fixed arm 43.
Fourth Embodiment
[0087] FIG. 12 illustrates structure of the tuning fork vibrating
piece 50 used for the tuning fork vibrator according to the fourth
embodiment. Note that, similarly to in FIG. 10 etc., in FIG. 12,
different patterns are attached to the excitation electrode
55.sub.1 and the excitation electrode 55.sub.2 in order to make a
layout of each excitation electrode 55 intelligible.
[0088] As depicted in FIG. 12, a tuning fork vibrating piece 50
used for a tuning fork vibrator according to the fourth embodiment
includes a base 51 and two vibrating arms 52.sub.1 and 52.sub.2
extending in parallel from the base 51. Further, the tuning fork
vibrating piece 50 also includes a first fixed arm 53.sub.1 and a
second fixed arm 53.sub.2 extending obliquely from the base 51 so
as to interpose the two vibrating arms 52 (52.sub.1 and
52.sub.2).
[0089] Grooves (only parts of the grooves are illustrated in FIG.
11) are formed on the three outside surfaces (the uppermost
surface, the lowermost surface and the surface which connects them
in FIG. 11), and two kinds of excitation electrodes 55.sub.1 and
55.sub.2 are formed on each surface of each vibrating arm 52.
[0090] On the tip part of the undersurface of the first fixed arm
53.sub.1 of the tuning fork vibrating piece 50, provided is a first
terminal 56.sub.1 that is electrically connected with the
excitation electrode 55.sub.1. On the tip part of the undersurface
of the second fixed arm 53.sub.2, provided is a first terminal
46.sub.2 that is electrically connected with the excitation
electrode 55.sub.2.
[0091] And, the tuning fork vibrator according to the present
embodiment is configured by housing and fixing the tuning fork
vibrating piece 50 in the package having the same structure as the
package 60 (FIG. 4) for the tuning fork vibrator 11 according to
the first embodiment using a housing and fixing method similar to
that for the tuning fork vibrator 20.
[0092] As obvious from the discussion given above, the tuning fork
vibrator according to the fourth embodiment exerts the action
effect of the tuning fork vibrator 20 according to the first
embodiment and the action effect of the tuning fork vibrator
according to the third embodiment.
[0093] Consequently, by adopting the structure of the tuning fork
vibrator according to the present embodiment, it is possible to
provide a tuning fork vibrator which has a size approximately equal
to that of the conventional ones and of which oscillation stability
is very high, a tuning fork vibrator of which oscillation stability
is approximately equal to that of the conventional ones and which
is very small, or the like.
Modified Examples
[0094] The tuning fork vibrator according to each of the
above-mentioned embodiments can be modified in a variety of forms.
For instance, the tuning fork vibrator according to the first,
second or fourth embodiment can be modified into the one including
the tuning fork vibrating piece having the first, second fixed arms
whose length and/or extending angle (angle from the vibrating arm)
are(is) different from those of the embodiment. However, it is
preferable to configure the tuning fork vibrator to have such a
shape that a plane that passes through the center of gravity of the
tuning fork vibrating piece and is perpendicular to the extending
direction crosses the tip part of the first fixed arm and the tip
part of the second fixed arm in order to be able to reduce the
amount of vibrations at the time of external force being added.
Note that an example of the tuning fork vibrator that satisfies
above condition is the one having the tuning fork vibrating peace
20 whose first fixed arm 21.sub.1 and second fixed arm 21.sub.2 are
respectively extended to the top right corner and the top-left
corner in FIG. 4.
[0095] The tuning fork vibrator according to the first, second or
fourth embodiment can also be modified into the one including the
tuning fork vibrating piece that dose not have the first and second
terminal provided on the tip parts of the fixed arms (the one
including the tuning fork vibrating piece having the fixed arms
each having tip part that is fixed to the package but is not used
for electric connection). Moreover, it is taken for granted that
the constituent material for the tuning fork vibrating piece may
not be a quartz crystal.
[0096] All examples and conditional language provided herein are
intended for the pedagogical purposes of aiding the reader in
understanding the invention and the concepts contributed by the
inventor to further the art, and are not to be construed as
limitations to such specifically recited examples and conditions,
nor does the organization of such examples in the specification
relate to a showing of the superiority and inferiority of the
invention. Although one or more embodiments) of the present
invention have been described in detail, it should be understood
that the various changes, substitutions, and alterations could be
made hereto without departing from the spirit and scope of the
invention.
* * * * *